The present invention relates to a flow rate control apparatus. More particularly, the present invention relates to a flow rate control apparatus for construction equipment for controlling a flow of hydraulic fluid supplied from a hydraulic pump to a work implement and an option actuator, and a control method therefor.
FIG. 1 is a hydraulic circuit diagram of a conventional flow rate control apparatus for construction equipment.
As shown in FIG. 1, first and second variable displacement hydraulic pumps 1 and 2 (hereinafter, referred as “first and second hydraulic pumps”) and a pilot pump 3 is connected to an engine 4.
A boom cylinder 5 driven by hydraulic fluid of the first hydraulic pump 1 is connected to the first hydraulic pump 1.
An option actuator 6 driven by hydraulic fluid of the second hydraulic pump 2 is connected to the second hydraulic pump 2.
A first control valve 7 (main control valve (MCV)) is provided in a fluid path between the first hydraulic pump 1 and the boom cylinder 5, and the first control valve controls a flow of the hydraulic fluid supplied from the first hydraulic pump 1 to the boom cylinder 5.
A second control valve 8 (MCV) is provided in a fluid path, between the second hydraulic pump 2 and the option actuator 6, and the second control valve controls a flow of the hydraulic fluid supplied from the second hydraulic pump 2 to the option actuator 6.
A boom cylinder manipulation lever 9 (remote control valve (RCV)) for inputting a manipulation signal to control the first control valve 7 is provided in a fluid path between the pilot pump 3 and the first control valve 7.
An option actuator manipulation lever (not shown) (RCV) for inputting a manipulation signal to control the second control valve 8 is provided in a fluid path, between the pilot pump 3 and the second control valve 8.
A confluence line 10 is connected at an inlet port thereof to a downstream side of a supply path of the first hydraulic pomp 1 and connected at an outlet port thereof to a meter-in port of the second control valve 8, and the confluence line 10 selectively loins a part of a flow rate supplied from the first hydraulic pump 1 to the boom cylinder 5 with allow rate of the option actuator 6.
A center bypass switching valve 11 (CBP) is provided in the furthest downstream side of the supply path of the first hydraulic pump 1, and an opening port thereof becomes closed when the center bypass switching valve 11 is operated by a pilot pressure applied by a manipulation of the boom cylinder manipulation lever 9.
According to the configuration described above, when the boom cylinder manipulation lever 9 is manipulated to perform a boom down operation by a retraction operation of the boom cylinder 5, the hydraulic fluid of the pilot pump 3 passes through the boom cylinder manipulation lever 9, and is applied to a right signal pressure port of the first control valve 7 as a pilot pressure.
In the figure, since a spool of the first control valve 7 is switched to a left direction, the hydraulic fluid of the first hydraulic pump 1 is supplied to a small chamber of the boom cylinder 5 by passing through the first control valve 7. Herein, the hydraulic fluid emitted from a large chamber of the boom cylinder 5 is returned to a hydraulic fluid tank T by passing through the first control valve 7.
Accordingly, the boom down operation is performed by the retraction operation of the boom cylinder 5.
Herein, a surplus flow rate, except for a flow rate required to perform the retraction operation of the boom cylinder 5 among the flow rate supplied from the first hydraulic pump 1, is returned to the hydraulic fluid tank T by passing through the center bypass switching valve 11.
As described above, when the retraction operation of the boom cylinder 5 is performed and a pressure generated in the large chamber of the boom cylinder 5 is equal to or less than a set pressure, a jack-up switching valve 12 maintains an initial state by elasticity of a valve spring thereof.
Accordingly, since the pilot pressure by the manipulation of the boom cylinder manipulation lever 9 is applied to an opposite side to a valve spring of the center bypass switching valve 11 by passing through the jack-up switching valve 12, the opening port of the center bypass switching valve 11 becomes closed.
Accordingly, the surplus flow rate of the flow rate supplied from the first hydraulic pump 1 to the small chamber of the boom cylinder 5 is supplied to the option actuator 6 by passing through the second control valve 8 along the confluence line 10.
As described above, when combined work is performed by driving the boom cylinder 5 to perform the boom down operation by the retraction operation of the boom cylinder 5, and by driving the option actuator 6 by the manipulation of the by the option actuator manipulation lever (not shown), the surplus flow rate of the flow rate supplied from the first hydraulic pump 1 to the small chamber of the boom cylinder 5 is supplied to the flow rate of the option actuator 6, thus fee performance of the option actuator 6 is interfered. In addition, when a jack up operation is performed by a retraction of the boom cylinder 5, the manipulability therefor is degraded by an insufficient flow rate supplied to the small chamber of the boom cylinder 5.
Accordingly, it is desirable to provide a flow rate control apparatus for construction equipment, wherein the flow rate control apparatus blocks a surplus flow rate of a boom down operation which being supplied to an option actuator when combined work of the boom down operation and an option actuator is performed, and a control method therefor.
According to an aspect of the present disclosure, there is provided a flow rate control apparatus for construction equipment, including:
first and second variable displacement hydraulic pumps and a pilot pump;
a boom cylinder driven by a hydraulic fluid of the first hydraulic pump;
a first control valve controlling a flow of the hydraulic fluid supplied from the first hydraulic pump to the boom cylinder;
an option actuator driven by a hydraulic fluid of the second hydraulic pump;
a second control valve controlling a flow of the hydraulic fluid supplied from the second hydraulic pump to the option actuator;
a boom cylinder manipulation lever for inputting a manipulation signal to control the first control valve, and an option actuator manipulation lever for inputting a manipulation signal to control the second control valve;
a confluence line connected at an inlet port thereof to a downstream side of a supply path of the first hydraulic pump, and connected at an outlet port thereof to a meter-in port of the second control valve;
a center bypass switching valve provided in the furthest downstream side of the supply path of the first hydraulic pump, and operated to close an opening port thereof by a pilot pressure applied thereto;
a confluence switching valve provided in the confluence line, and joining a part of the hydraulic fluid supplied from the first hydraulic pump to the boom cylinder with the hydraulic fluid of the option actuator when the confluence switching valve is operated to open an opening port thereof;
a confluence selection valve provided in a fluid path between the pilot pump and the confluence switching valve, and applying the pilot pressure to the confluence switching valve when the confluence switching valve is operated; and
a controller controlling the confluence selection valve to block the pilot pressure supplied from the pilot pump to the confluence switching valve so that the confluence line becomes closed when combined work of the boom cylinder and the option actuator is performed.
According to another aspect of the present disclosure, there is provided a flow rate control apparatus for construction equipment, the apparatus including:
first and second variable displacement hydraulic pumps and a pilot pump;
a boom cylinder driven by a hydraulic fluid of the first hydraulic pump;
a first control valve controlling a flow of the hydraulic fluid supplied from the first hydraulic pump to the boom cylinder;
an option actuator driven by a hydraulic fluid of the second hydraulic pump;
a second control valve controlling a flow of the hydraulic fluid supplied from the second hydraulic pump to the option actuator;
a boom cylinder manipulation lever for inputting a manipulation signal to operate the first control valve, and an option actuator manipulation lever for inputting a manipulation signal to operate the second control valve;
a confluence line connected at an inlet port thereof to a downstream side a supply path of the first hydraulic pump, and connected at an outlet port thereof to a meter-in port of the second control valve;
a center bypass switching valve provided in the furthest downstream side of the supply path of the first hydraulic pump, and operated by a pilot pressure applied thereto so that an opening port thereof becomes closed; and
a confluence switching valve provided in the confluence line, and manually operated to open or close the confluence line,
According to another aspect of the present disclosure, there is provided a flow rate control method of construction equipment, wherein the construction equipment includes;
first and second variable displacement hydraulic pumps and a pilot pump;
a boom cylinder and an option actuator respectively connected to the first and second hydraulic pumps;
first and second control valves respectively controlling flows of a hydraulic fluid supplied to the boom cylinder and the option actuator;
a boom cylinder manipulation lever and an option actuator manipulation lever;
a confluence line selectively supplying the hydraulic fluid of the first hydraulic pump to the hydraulic fluid of the second hydraulic pump;
a confluence switching valve opening and closing the confluence line;
a confluence selection valve provided in a fluid path between the pilot pump and the confluence switching valve;
first and second pressure sensors respectively detecting pilot pressures applied to the first and second control valves by manipulations of the boom cylinder manipulation lever and the option actuator manipulation lever; and
a controller connected to the first and second pressure sensors and the confluence selection valve, the method comprising;
receiving manipulation signals from the boom cylinder manipulation lever and the option actuator manipulation lever for driving the boom cylinder and the option actuator;
determining whether or not combined work of the boom cylinder and the option actuator is performed by using signals indicative of detection results of the first and second pressure sensors; and
blocking a pilot pressure applied to the confluence switching valve so that the confluence line becomes closed when the combined work of the boom cylinder and the option actuator is performed.
According to the present invention including the above configuration, there is an effect on preventing performance interference of an option actuator caused by a surplus flow rate supplied from a boom down operation when a combined work of the boom down operation and an option actuator is performed, or preventing degradation of the manipulability due to an insufficient flow rate supplied to the boom cylinder.